Yeah a lot of those fancy PDF features are Adobe-only. It's not that other apps can't support those features, it's that no one in their right mind wants to spend endless amounts of money and time trying to sandbox it.

Most people have some understanding that shady websites can give you malware, a drive-by exploit is pretty rare but it's good that most people think just visiting a site could infect your computer. But a PDF is just a document, right? Just thinking that a PDF is just words on a page is exactly why it's such an insidious threat. Or they'll get a PDF as an email attachment, see that it's not an exe or something weird, and open it because they think a document is safe.

I think it's more the image formats PDF supports? I could be wrong, but there was that forcedentry vulnerability (which was insanely cool, even if really bad)